Jeon Hae-rim was scouted by an agency when she was a senior high school student. The actress stated, "Ever since I was a little kid, I dreamed of becoming an actress. When I was a senior in high school, an agency contacted me after seeing my picture at a photography studio." She later graduated with a degree in Bachelor of Film and Television (BFTV) in Dankook University. In 2012, the actress revealed that she had failed over 100 auditions before her debut, "I passed my college entrance and written exams and was accepted to the department of theater and film. Before my debut, I auditioned for 100 or so projects but didn’t get the roles."[13]

Jeon candidly revealed that she adopted "Ha Ji-won" as her stage name as a favor for her previous manager as it was the name of his first love. "When I was about to debut, the first love of my manager's name was Ha Ji-won. I think he wanted to at least use the name of his love that was not fulfilled. The first time I heard the name Ha Ji-won, I thought it was pretty and also bold."[14]

Ha Ji-won made her TV debut in the 1996 teen drama, New Generation Report: Adults Don’t Understand Us. She continued playing supporting roles in dramas, Dragon's Tears and Dangerous Lullaby in 1998 and 1999 respectively. But it was through the popular high school drama School 2, in which she played the role of a troubled teen named Jang Se-jin, that she started to gain fame as an actress.[15]

In 2001, Han had her first leading role in Beautiful Life, where she played the role of a chaebol hotelier's daughter, opposite Kim Rae-won. This was followed by another starring role in Days in the Sun opposite Ji Sung.

In 2003, Ha starred in the movie, Reversal of Fortune, alongside Kim Seung-woo. She then participated in her first historical drama, Damo. Ha's performance as a lowly police detective was highly praised and she was given the Top Excellence award at the MBC Drama Awards.[23] The series became a popular sensation online, gaining fame among viewers in their 20s and 30s, and becoming the first Korean drama in the Internet era to reach 1 million posts on the message board of its official website, which caused the site's servers to crash. As a result, Ha's popularity skyrocketed.

In 2006, Ha starred in the critically acclaimed period drama, Hwang Jin Yi, based on the real-life history of the character. She played the titular character Hwang Jin Yi, who lived in 16th-century Joseon and is considered the most famous gisaeng in the Korean history. The series was a huge ratings success, giving rise to a boom in gisaeng-themed entertainment—musicals, TV dramas, films, even cartoons. Ha's portrayal of the character was positively reviewed by critics and audience, and she bagged a total of 5 awards for her performance, including the Best Actress award at the 34th Korean Broadcasting Awards and the Daesang (Grand Prize) honor at the 2006 KBS Drama Awards.

In 2007, Ha reunited with Director Yoon Je-kyoon and Im Chang-jung in the comedy film, Miracle on 1st Street, and challenged herself in the role of a female boxer. Coming from the team behind Sex Is Zero, the movie ended up as the 5th most popular movie in that year.[25] Later that year, Ha made a cameo appearance in Sex Is Zero 2, sequel of Sex Is Zero, reprising her role in the movie.

In 2009, Ha worked with Director Yoon Je-kyoon for the third time through the blockbuster disaster filmHaeundae, alongside A-list actors Sol Kyung-gu, Park Joong-hoon, and Uhm Jung-hwa. The movie was funded by CJ Entertainment with a budget estimated at US$10–15 million, one of the largest for a Korean production.[26]Haeundae was both critically acclaimed and a commercial success. It received a total of 11,301,649 admissions in South Korean theaters, making it the 4th highest-grossing film in South Korea then, and giving Ha the honor of "The 10 Million Movie Actress" for bringing the glory of more than 10 million audiences. In addition to that, distribution rights for the movie have been sold to 15 countries. Later in the year, she starred in Park Jin-pyo's Closer to Heaven, a melodrama movie about a man who has been battling Lou Gehrig's disease and his loving wife, who works as a funeral director (played by Ha). Ha's heartfelt performance in the film won her the Best Actress Award at the 30th Blue Dragon Film Awards and 46th Baeksang Arts Awards, officially establishing her position as an A-list film actress.

After taking a 4-year break from dramas, Ha made a very successful comeback through the 2011 hit drama, Secret Garden, written by famous writer Kim Eun-sook. She played the role of a stunt woman Gil Ra-im, who magically switches bodies with a wealthy CEO character, played by Hyun Bin. Proven to be a commercial success, the drama series achieved high ratings and rights to the broadcast had been sold abroad before its premiere in South Korea, contributing to Ha's rise in popularity overseas. Ha received numerous recognition at local award-giving bodies, including the prestige Best Actress at the Grimae Awards, an honorable award chosen by directors in every broadcasting station in Korea.

Once again, Ha worked with Director Yoon Je-kyoon and Ahn Sung-ki through the science fiction3D movie, Sector 7. Although the film failed to do well in South Korea, it was a hit in China, garnering over 20 million yuan in China after just one week, beating previous records set by 200 Pounds Beauty at 16 million yuan.[27] Ha later revealed that she had had received psychiatric treatment after filming Sector 7, as she was too immersed in the role.[28]

In 2012, Ha starred in alternate history drama The King 2 Hearts opposite Lee Seung-gi, playing the role of a North Korean Special Forces Officer who married a South Korean crown prince as a political strategy. The drama also reunited Ha with Director Lee Jae-kyoo, who had previously directed Damo. Despite the drama's decreasing viewership ratings, Ha and Lee were both praised for their performance. It was also revealed that Ha had studied the North Korean dialect to make her portrayal of the character more realistic and genuine.[29] Ha then acted in sports drama film As One, playing the role of a South Korean table tennis player. It was reported that Hyun Jung-hwa, whom Ha portrayed in the film, picked her as the first choice to portray the role.[30] Ha trained for three months in table tennis, keeping up with the highly intensive training. She also observed Hyun's speech and body language carefully, striving to embody all of her playing habits and techniques. As Ha had simultaneously portrayed a North and South Korean character on the small and big screen,[31] she was dubbed as "The Flower of Reunification" for crossing boundaries of the two nation.[32]

The following year, in 2013, Ha was reported to be leaving Wellmade STARM, her agency for 10 years. She declined all the love calls sent by other agencies with giant contracts and decided to establish her own one-person agency Haewadal Entertainment (lit. Sun and Moon Entertainment) instead.[33] Also in the same year, Ha signed with United Talent Agency, one of the largest talent agencies in the world, for her Hollywood venture. Haewadal Entertainment released a statement saying, "Ha Ji Won became the first female Korean star to sign with one of Hollywood's largest agencies UTA and plan to kick off her advancement overseas in full-swing."[34]

In 2013, Ha returned to saeguk drama through Empress Ki, taking on the titular role of the empress. The 51-episode drama is a fictional account about the love and struggles of a Goryeo born woman named Ki Seung-nyang and her long journey to becoming Yuan dynasty's Empress Ki. Throughout its entire run on MBC that lasted six months, Empress Ki achieved high viewership ratings and Ha's portrayal of the empress was highly praised. At the MBC Drama Awards, Ha won her second Daesang award throughout her career for her performance in the drama, as well as the Actress of the Year. The historical drama was also well-received overseas; particularly in Taiwan, the drama reached a peak rating of 5.35%, making it the second Korean drama to surpass the 5 percent mark in ratings after Dae Jang Geum's 6.22% in 2004.[35]

After establishing her own agency, Haewadal Entertainment, Ha simultaneously signed a contract with BM+ Entertainment to manage her activities abroad. BM+ Entertainment stated, "We have a contract with Ha Ji Won for her television, movie, cf, and function activities in South Korea and abroad."[37]

In 2015, Ha was cast by Ha Jung-woo to play his character's wife in his self-directed movie, Chronicle of a Blood Merchant, a film adaption of the bestselling 1995 Chinese novel of the same title written by Yu Hua.[38] Following that, Ha, alongside actor Lee Jin-wook starred in the Korean remake of the 2011 hit Taiwanese dramaIn Time with You titled The Time We Were Not in Love.[39] She reportedly earned a salary of 50 million won or approximately US$43,000 per episode of the drama, making her one of the highest paid actresses in South Korean television.[40] However, in contrast to her previous dramas, The Time We Were Not in Love received low ratings. Nonetheless, Ha said she was satisfied with the drama and enjoyed the filming process as she considered her character Oh Ha-na the closest to her real life personality.[41]

In the same year, Ha signed with Invincible Plan to manage her Chinese ventures.[42]

Ha has completed filming her upcoming Korea-China co-production film, Risking Life For Love, costarring Taiwanese actor Bolin Chen and fellow Korean actor Chun Jung-myung.[43] The film is scheduled to be released in the first half of 2016.

In 2016, Ha is cast for Manhunt, a Hollywood production by famed director John Woo about a small district office prosecutor who has been framed for a crime he didn’t commit and then sets out to prove his innocence. She will be starring alongside Asia's superstars Louis Koo, Leon Lai, Daniel Wu and Li Bingbing.

After an eight-year hiatus on stage, Ha performed with her labelmates AA for their debut at the K-pop Super Concert in 2011.[47]

On June 13, 2014, Ha released a digital single, Now In This Place, for the fans who had been so supportive of her drama Empress Ki. The lyrics of the song was written by the scriptwriter of Empress Ki, Jung Kyung Soon. The song was composed and produced by popular music producer Jae Chong (also known as Jung Jae-yoon).[48]

In June 2015, Ha released a self-written song, You Are Zoe, featuring ZE:A's Heechul. She personally wrote the song while working on OnStyle's Go Go with Sister in Grasse, France. The track was composed by singer The Film.[49]

Ha does charity work with her fans on a regular basis.[56] such as delivering coal to Bangbae-dong,[57]

Although organ donation was not common in South Korea at that time in January 2005, Ha Ji-won made the pledge to donate her cornea through the Organ Donation Center of Love. The actress shared, "When I was in crisis of becoming blind in May of 2004 because of damaged cornea in my left eye while filming, but one prisoner sent me a letter expressing his willing to donate his own cornea to me, I was very thankful and greatly touched. I want to be of help to the visually impaired. It's shocking and pitiful that we import cornea from other countries."[58]

Ha has also played an active role in helping underprivileged and disabled children, running a donation project named Smile Again Foundation with Gangnam-gu Family Welfare Center. The project was supplemented by Ha Ji-won's fan club members while she went the extra mile to ensure the sustainability of the project.[59] Ha was conferred the Prime Minister's Award for the '2008 Family Month Event', in recognition of her consistent and active hard work in contributing to programs for poor and handicapped families.[60]

In 2012, Ha donated the proceeds from her first book, At This Moment, to charity. The recipients of the book earnings, children's aid group Choi Kyung Joo Foundation and Yonsei University Hospital, announced their decision to set up a scholarship for prospective arts students and to subsidize treatment for deaf and blind children respectively. Sponsored by Ha, the organization has set up a "Hartist" (Ha + artist) scholarship to sponsor students who dream of careers in art.[61]

Together with fellow actor Song Joong-ki, Ha attended Medical Korea 2013 Sharing Medical Treatment Commemorative Event, an event hosted by the Ministry of Health and Welfare, promoting greater international co-operation for medical technology and positive medical tourism. During the event, both actors spent time with recovering children and received an award for their previous efforts in promoting the sharing of medical services.[62]

In 2015, Ha, fashion icon Ko So-young, and figure skatingKim Yuna designed bags in cooperation with the Italian luxury brand Fendi. The bags were offered via Seoul Peekaboo Project auction to raise funds for the charity. As Operation Smile's Ambassador, Ha decided to donate the proceeds from the bag she designed to Operation Smile, a NGO that performs cleft lip and cleft palate surgery and delivers postoperative and ongoing medical therapies to children in low and middle income countries.[63]